1. Field of Invention
The present invention relates to an apparatus for manufacturing an optical device.
2. Description of Related Art
A related art projector includes a plurality of light modulators (liquid crystal panels) to modulate a plurality of colored light rays in accordance with image information; a color-combining optical system (cross dichroic prism) to combine the colored light rays modulated by the light modulators; and a projection optical system (projection lens) to enlarge and project luminous fluxes generated at the color-combining optical system so as to form a projected image. An example of this type of projector is a so-called three-panel-type projector, in which a luminous flux emitted from a light source is separated into light rays of three colors of red, green, and blue, by a dichroic mirror, each of the light rays is modulated by each of three liquid crystal panels in accordance with image information, the luminous fluxes after modulation are combined by a cross dichroic prism, and a color image is enlarged and projected by a projection lens.
In order to obtain a clear projection image with the projector, mutual focus/alignment adjustment of each of the liquid crystal panels must be performed with high accuracy when the projector is manufactured, so as to reduce or prevent misalignment of pixels in each of the liquid crystal panels and displacement in the distance from the projection lens. The xe2x80x9cfocus adjustmentxe2x80x9d means adjustment to accurately place each of the liquid crystal panels at a back focus position of the projection lens. The xe2x80x9calignment adjustmentxe2x80x9d means adjustment to match the pixels of each of the liquid crystal panels. This is also applied to the description below.
Focus/alignment adjustment of the liquid crystal panels is performed for an optical device including the three liquid crystal panels and a cross dichroic prism, by (1) radiating a luminous flux from a metal halide lamp as an adjusting light source device to an image forming region of each of the liquid crystal panels, (2) detecting the luminous flux which enters a light-incident surface of the cross dichroic prism and which is emitted from a light-emitting surface thereof by a luminous flux detector such as a CCD camera, and (3) adjusting the relative positions of the liquid crystal panels by a position adjusting device, while the focus and pixel position of each of the liquid crystal panels, detected by the luminous flux detector, are checked.
Then, each of the liquid crystal panels, whose position is adjusted, is fixed by using ultraviolet curing adhesive so as to manufacture the optical device with high accuracy.
However, the metal halide lamp which is used as an adjusting light source device, and which is used for manufacturing the optical device, consumes a large amount of electrical power and is easily worn out. Accordingly, the cost of the adjusting light source device increases and as a result, the cost for the optical device increases. Furthermore, the metal halide lamp has a large external dimension, and thus the adjusting light source device cannot be miniaturized.
Accordingly, the present invention provides an apparatus for manufacturing an optical device in which energy can be saved and an inexpensive optical device can be manufactured by reducing the cost for an adjusting light source device and in which the adjusting light source device can be miniaturized.
An apparatus for manufacturing an optical device according to the present invention performs mutual position adjustment of each of a plurality of light modulators and fixes each of the light modulators to a light-incident surface of a color-combining optical system, in order to manufacture the optical device including the plurality of light modulators, each of which modulates each of a plurality of colored light rays according to image information, and the color-combining optical system to combine the colored light rays modulated in the light modulators. The apparatus includes an adjusting light source device including a plurality of light sources to supply colored light rays to be modulated to each of the light modulators; a luminous flux detector to detect a luminous flux emitted from the adjusting light source device and passed through each of the light modulators and the color-combining optical system; and a position adjusting device to adjust the position of each of the light modulators based on the luminous flux detected by the luminous flux detector. The light sources include self-light-emitting elements.
A CCD camera or the like, which includes an image pickup device such as a CCD, an image-taking device to take a signal detected by the image pickup device, and a processor to process the taken image, can be used as the luminous flux detector.
Also, various types of self-light-emitting elements, for example, a light-emitting diode (LED), an organic electro luminescence (EL) element, and a silicon light-emitting element can be used as the self-light-emitting elements. Any type of self-light-emitting element can be used as long as the element self-emits light semipermanently by being applied with a current, voltage, or electrical field externally.
Herein, the xe2x80x9cself-light-emitting elementxe2x80x9d means an element which emits light when electron transitions are caused between energy levels, and a generated luminous flux has a single wavelength. On the other hand, a range of wavelength recognized as colored light is: 588 nm or more for red light, 502 to 569 nm for green light, and 501 nm or less for blue light. Accordingly, in order to form a light source corresponding to each colored light ray, a wavelength as a single wavelength must be selected from within the range of wavelength corresponding to each colored light ray so as to specify the wavelength. For example, 613 nm for red light, 525 nm for green light, and 470 nm for blue light can be selected and specified.
The power consumption of a known metal halide lamp is about 150 W, and the life thereof is about 750 hours. On the other hand, an LED as a self-light-emitting element has a power consumption of about 3.6 W and the life is semipermanent. Also, a self-light-emitting element is not a discharge light source different from a metal halide lamp, and thus the external dimension is fairly small compared to that of the metal halide lamp. Accordingly, a self-light-emitting element is greatly different from a metal halide lamp in the points of power consumption, life, and external dimension.
According to the present invention, since the above-described self-light-emitting element is adopted as the light source of the adjusting light source device, the power consumption when the optical device is manufactured can be reduced compared to the case where a known metal halide lamp is used. Also, the self-light-emitting element can be used semipermanently as the light source of the adjusting light source device. Therefore, energy can be saved, the cost for the adjusting light source device can be reduced, and thus the cost for manufacturing the optical device can be reduced. In addition, the adjusting light source device and the apparatus for manufacturing the optical device can be miniaturized.
Preferably, the adjusting light source device includes a diffusion plate on the subsequent stage of each of the light sources in the apparatus for manufacturing the optical device.
In general, the luminous flux emitted from the self-light-emitting element is a diffused light without directivity. Thus, when the light source has a spherical casing to accommodate a self-light-emitting element, and when a diffused light from the self-light-emitting element is directly radiated to the light modulator, such as a liquid crystal panel, the light is projected in substantially a circular-shape due to the spherical-shape of the light source in each of rectangular pixels in the image forming region of the liquid crystal panel. Thus, four corners of each pixel are not projected adequately.
However, by placing the diffusion plate on the subsequent stage of the self-light-emitting element, the diffused light emitted from the self-light-emitting element so as to project the light modulators in a spherical shape can be converted to diffused light corresponding to the shape of the light modulators by the diffusion plate. Thus, the whole of the light modulators can be projected accurately. Accordingly, accurate detection can be performed by the luminous flux detector, and thus the optical device can be manufactured with higher accuracy.
Preferably, the light-emitting elements are placed corresponding to four corners of the rectangular image forming region of each of the light modulators.
In this case, when the light-emitting elements emit light to the four corners of the image forming region and the corresponding luminous flux detector detects the four corners, a plurality of pixel regions in one light modulator can be detected. Accordingly, adjustment can be performed with high accuracy by the position adjusting device based on the detection result at all imaging points.
Further, the self-light-emitting element is preferably a light-emitting device (LED).
Herein, the LED has three advantages: first, three types of LED, that is, red, green, and blue, can be easily made simply by changing the semiconductor material or additives; second, the LED does not generate heat; and third, the light emission can be switched ON/OFF rapidly.
Accordingly, by using the LED, an optical device to modulate light rays of three colors can be easily manufactured with the first advantage. Also, overheating in other portions in the apparatus can be reduced or prevented and the apparatus can be easily used with the second advantage. Further, the optical device can be rapidly manufactured with the third advantage.
Preferably, the plurality of light sources includes a red LED, a green LED, and a blue LED.
With this arrangement, by preparing three light modulators to modulate each of red light, green light, and blue light, and by providing the color LED for each of the three light modulators, the optical device which can perform full-color output can be easily manufactured.